Coupling Topological Insulator SnSb₂Te₄ Nanodots with Highly Doped Graphene for High-Rate Energy Storage

Topological insulators have spurred worldwide interest, but their advantageous properties have scarcely been explored in terms of electrochemical energy storage, and their high-rate capability and long-term cycling stability still remain a significant challenge to harvest. p-Type topological insulator SnSb₂Te₄ nanodots anchoring on few-layered graphene (SnSb₂Te₄/G) are synthesized as a stable anode for high-rate lithium-ion batteries and potassium-ion batteries through a ball-milling method. These SnSb₂Te₄/G composite electrodes show ultralong cycle lifespan (478 mAh g⁻¹ at 1 A g⁻¹ after 1000 cycles) and excellent rate capability (remaining 373 mAh g⁻¹ even at 10 A g⁻¹) in Li-ion storage owing to the rapid ion transport accelerated by the PN heterojunction, virtual electron highways provided by the conductive topological surface state, and extraordinary pseudocapacitive contribution, whose excellent phase reversibility is confirmed by synchrotron in situ X-ray powder diffraction. Surprisingly, durable lifespan even at practical levels of mass loading (>10 mg cm⁻²) for Li-ion storage and excellent K-ion storage performance are also observed. This work provides new insights for designing high-rate electrode materials by boosting conductive topological surfaces, atomic doping, and the interface interaction. © 2019 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.